Fluid pump having bearing hold

ABSTRACT

A fluid pump includes a stationary part. A rotator is rotatable around the inner circumferential periphery of the stationary part. One of the stationary part and the rotator includes at least one coil that generates magnetic force between the stationary part and the rotator for rotating the rotator when being supplied with electricity. A pump portion is provided to one axial end of the rotation axis of the rotator. A cover covers the other axial end of the rotation axis of the rotator and the stationary part. The cover defines an outlet passage through which fluid is discharged from the pump portion. The cover has a bearing hole that rotatably supports the other axial end of the rotation axis. The bearing hole has a closed bottom. The cover has a communication passage that communicates the outlet passage with the bearing hole.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and incorporates herein by referenceJapanese Patent Applications No. 2005-257416 filed on Sep. 6, 2005, No.2005-302698 filed on Oct. 18, 2005, No. 2005-315974 filed on Oct. 31,2005, No. 2005-347593 filed on Dec. 1, 2005, No. 2005-363423 filed onDec. 16, 2005, No. 2006-154435 filed on Jun. 2, 2006, and No.2006-171173 filed on Jun. 21, 2006.

FIELD OF THE INVENTION

The present invention relates to a fluid pump having a bearing hole.

BACKGROUND OF THE INVENTION

According to U.S. 2005/0074343 A1 (JP-A-2005-110478), the fuel pumpincludes the pump portion that is driven by rotative force of the motorportion for pumping fuel. In this structure, a cover surrounds the axialend of the motor portion on the opposite side of the pump portion. Themotor portion includes a brushless motor. The cover has the outlet portthrough which fuel is discharged. The cover has the bearing thatrotatably supports the rotation axis of the rotator of the motorportion.

The cover has the bearing hole accommodating the bearing. The bearinghole is blocked at the bottom thereof. In this structure, fuelaccumulating in the bearing hole may be deteriorated, and the rotationaxis may be corroded due to the deteriorated fuel. Furthermore, foreignmatters such as debris caused by ablation in the fuel pump mayaccumulate in the bearing hole. Consequently, the foreign matters may bestuck in the sliding portion between the rotation axis and the bearing,for example.

SUMMARY OF THE INVENTION

In view of the foregoing and other problems, it is an object of thepresent invention to produce a fluid pump having a bearing hole, inwhich fuel and foreign matters can be restricted from accumulating.

According to one aspect of the present invention, a fluid pump includesa stationary part that has an inner circumferential periphery. The fluidpump further includes a rotator that is rotatable around the innercircumferential periphery. The rotator has a rotation axis. One of thestationary part and the rotator includes at least one coil. The at leastone coil generates magnetic force between the stationary part and therotator for rotating the rotator when being supplied with electricity.The fluid pump further includes a pump portion that is provided to oneaxial end of the rotation axis of the rotator. The rotator is adapted torotating the pump portion for pumping fluid. The fluid pump furtherincludes a cover that covers an other axial end of the rotation axis ofthe rotator. The cover covers the stationary part on a side of the otheraxial end of the rotation axis. The cover defines an outlet passagethrough which fluid is discharged from the pump portion. The cover has abearing hole that rotatably supports the other axial end of the rotationaxis. The bearing hole has a closed bottom. The cover has acommunication passage that communicates the outlet passage with thebearing hole.

Alternatively, the bearing hole substantially may axially extend to aclosed axial end in the cover. The closed axial end may block thebearing hole with respect to an axial direction of the bearing hole.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a longitudinal partially sectional view showing a fuel pumpaccording to a first embodiment;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a schematic sectional view showing an end cover of a fuel pumpaccording to a second embodiment;

FIG. 5 is a schematic sectional view showing an end cover of a fuel pumpaccording to a third embodiment; and

FIG. 6 is a sectional view showing a fuel pump according to a fourthembodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment

As shown in FIG. 1, a fuel pump 10 of this embodiment is an in-tankturbine pump, for example. The fuel pump 10 is provided in a fuel tankof a motorcycle with an engine size of 150 cc, for example.

The fuel pump 10 includes a pump portion 12 and a motor portion 13. Themotor portion 13 rotates the pump portion 12. The housing 14 serves as ahousing. The housing 14 accommodates both the pump portion 12 and themotor portion 13. A pump case 20 and an end cover 50 are fixed bycrimping axially both ends of the housing 14. The end cover 50 serves asa cover. The thickness of a portion of the housing 14 covering the outercircumferential periphery of a stator core 30 in the motor portion 13 isless than the thickness of a portion defining a step 15 in the pumpportion 12. The stator core 30 may serve as a stationary part. Thehousing 14 is not necessary for defining a magnetic circuit. In thisstructure, the thickness of the housing 14 surrounding the outercircumferential periphery of the stator core 30 can be reduced, so thatthe outer diameter of the motor portion 13 can be reduced.

The pump portion 12 serves as a turbine pump. The pump portion 12includes pump cases 20, 22, and an impeller 24. The pump case 22 isabutted axially onto the step 15 of the housing 14, so that the pumpcase 22 is axially aligned. A bearing 26 is press-inserted into thecenter of the pump case 22. The pump case 20 is fixed by crimping oneend of the housing 14. Axial force is caused by the crimping, therebyproducing pressure for axially pressing the pump case 22 and the pumpcase 20 respectively onto the step 15 and the pump case 22, so that fuelis sealed.

The pump cases 20, 22 rotatably accommodates the impeller 24 as a rotormember. The pump cases 20, 22 and the impeller 24 define pump passages202 in substantially C-shapes thereamong. Fuel is drawn through an inletport 200 provided to the pump case 20, and is pressurized through thepump passages 202 by rotation of the impeller 24, thereby beingpress-fed toward the motor portion 13. The fuel press-fed toward themotor portion 13 is supplied toward an engine through an outlet port 208after passing through a fuel passage 204 and an outlet passage 206. Thefuel passage 204 is defined between the stator core 30 and a rotator 70.The outlet port 208 communicates the outlet passage 206 with the outsideof the end cover 50. The outlet port 208 is eccentric with respect to abearing hole (bearing) 52.

The motor portion 13 is a brushless motor that includes the stator core30, bobbins 40, coils 42, and the rotator 70. The stator core 30 isconstructed of six cores 32 that are circumferentially arranged. Anunillustrated control apparatus controls current supplied to the coils42 in accordance with a rotational position of the rotator 70, therebyswitching magnetic poles defined in the inner circumferentialperipheries of the cores 32. The inner circumferential peripheries ofthe cores 32 are opposed to the outer circumferential periphery of therotator 70.

As shown in FIG. 2, each of the cores 32 has a tooth 33 and an outercircumferential periphery 34. Each core 32 is integrally formed bycrimping magnetic steel plates, which are stacked with respect to theaxial direction of the shaft 72. The shaft 72 serves as a rotation axis.The tooth 33 protrudes from the center of the outer circumferentialperiphery 34 inwardly toward the rotator 70. Each of the bobbins 40formed of electrically insulative resin engages with each of the cores32. Six of the outer circumferential peripheries 34 define a toroidalcore. Each of the outer circumferential peripheries 34 is in asubstantially arc shape that has a circumferentially substantiallyregular width.

Each of the coils 42 is constructed by concentrically winding a wirearound the outer periphery of the bobbin 40 of each of the cores 32 in acondition where each of the six cores 32 is a single component beforebeing circumferentially arranged to be the stator core 30. Each of thecoils 42 electrically connects with each of terminals 44, 45 on the sideof the end cover 50 depicted in FIG. 1. The terminals 44 are taken fromjunctions electrically connecting with the coils 42 to the outside ofthe end cover 50, thereby being exposed from the end cover 50. Theterminals 44 connect with a connector. The terminals 45 are not exposedfrom the end cover 50. The terminals 45 electrically connect the coils42 with each other.

The bearing hole 52 is defined in the center of the end cover 50. Theterminals 44, 45 are inserted molded in the end cover 50 at locationsspaced from the bearing hole 52 by substantially constant distances forsecuring distances from the housing 14 in order to secure insulationfrom the metallic housing 14 located on the radially outer side. Theterminals 44 are bent such that the terminals 44 are taken from theinside of the end cover 50 to the outside at a location in which theterminals 44 are exposed on the radially outer side with respect to thelocations of the terminals 44 inside the end cover 50.

The terminals 44 are bent such that the terminals 44 are exposed fromthe radially outer side with respect to the location of the terminals 44inside the end cover 50. The outlet port 208 is eccentric with respectto the bearing hole 52, so that the outlet port 208 is spaced from thecenter of the end cover 50. Therefore, the terminals 44, which areexposed from the surface of the end cover 50, can be possibly spacedfrom the outlet port 208.

Here, the bearing hole 52 may be coaxial with respect to the outlet port208 of the outlet passage 206 opening in the surface of the end cover50. That is, the outlet port 208 may be defined in the center of the endcover 50. In this structure, when components such as the terminals 44are provided to the surface of the end cover 50 other than the outletport 208, alternatively when the components are taken from the inside ofthe end cover 50 to a portion other than the outlet port 208, thedistance between the terminals 44 and the outlet port 208 may be lessthan the radius of the end cover 50, even spaced at most. Accordingly,the distance between the outlet port 208 and the other component issmall, particularly in a small fuel pump. Consequently, for example, aspace for connecting the terminals 44 with a connector or a space forconnecting the outlet port 208 with a pipe or the like becomes small.Accordingly, manufacturing work for connecting the fuel pump with theother component becomes difficult.

By contrast, in this embodiment, the outlet port 208 of the outletpassage 206 is eccentric with respect to the bearing hole 52, so thatthe outlet port 208 is spaced from the center of the end cover 50.Therefore, components such as the terminals 44 arranged in the surfaceof the end cover 50 can be possibly spaced from the outlet port 208.Alternatively, when components are taken from the inside of the endcover 50 to a location other than the outlet port 208, the location canbe possibly spaced from the outlet port 208.

Therefore, the terminals 44, which are exposed from the surface of theend cover 50, can be possibly spaced from the outlet port 208. Thus,connection of the terminals 44 with the connectors can be facilitated,and connection of the outlet port 208 with a pipe or the like can bealso facilitated.

The structure of this embodiment may be effective to a small fuel pump,in particular.

An electrically insulative resin material 46 is charged between theteeth 33, which are circumferentially adjacent to each other, therebybeing molded such that the electrically insulative resin material 46covers the coils 42. The electrically insulative resin material 46 isintegrally molded with the end cover 50, which covers the end of thestator core 30 on the opposite side of the pump portion 12 with respectto the stator core 30. The electrically insulative resin material 46 maybe poly phenylene sulfide (PPS) or poly acetal (POM). The end cover 50is molded of the electrically insulative resin material 46 integrallywith the bearing hole 52, which rotatably supports the shaft 72, asupporting portion of the terminals 44, and the outlet port 208. Theelectrically insulative resin material 46 is integrally molded with theend cover 50, so that the number of components constructing the fuelpump 10 can be reduced, and manufacturing work for assembling the fuelpump 10 can be reduced.

The end cover 50 has the bearing hole 52 in the center thereof forrotatably support the shaft 72. The bearing hole 52 directly supportsthe shaft 72. The bottom of the bearing hole 52 is blocked. The endcover 50 has the outlet passage 206 eccentrically with respect to thebearing hole 52. The outlet passage 206 linearly penetrates the endcover 50 substantially in the axial direction of the end cover 50. Theoutlet passage 206 and the bearing hole 52 directly overlap, so that theoutlet passage 206 communicates with the bearing hole 52.

A slant restriction member 60 is in a substantially annular shapedefining a through hole at the center thereof. The slant restrictionmember 60 hooks to the end of the bobbin 40 on the opposite side of thepump portion 12. The slant restriction member 60 has fitting holes towhich the terminals 44, 45 fit. The electrically insulative resinmaterial 46 is molded in a condition where the terminals 44, 45 fit tothe fitting holes, so that the terminals 44, 45 can be restricted frombeing inclined and causing interference with peripheral components whenthe electrically insulative resin material 46 is molded.

As referred to FIGS. 1, 2, the rotator 70 includes the shaft 72 and apermanent magnet 74. The rotator 70 is rotatable around the innercircumferential periphery of the stator core 30. The shaft 72 isrotatably supported by the bearing 26 at one end, and is rotatablysupported by the bearing hole 52 at the other end. The permanent magnet74 is a resin magnet that is produced by mixing magnetic powder withthermoplastic resin such as polyphenylene sulfide (PPS) and shaping itto be cylindrical. The shaft 72 has a knurled outer circumferentialperiphery to which the permanent magnet 74 is directly formed byinjection molding or the like. The permanent magnet 74 has eightmagnetic poles 75 arranged with respect to the rotative direction of therotator 70. The eight magnetic poles 75 are magnetized to definemagnetic poles in the outer circumferential periphery opposed to thestator core 30. The magnetic poles are different from each other withrespect to the rotative direction of the rotator 70.

The end cover 50 has the outlet port 208 that accommodates a valvemember 80, a stopper 82, and a spring 84 that construct a check valve.Thus, the end cover 50 also serves as a housing of the check valve, sothat the number of the components constructing the fuel pump 10 can bereduced, and manufacturing work for assembling the fuel pump 10 can bereduced.

The valve member 80 is lifted against bias force of the spring 84 whenpressure of fuel pressurized in the pump portion 12 becomes equal to orgreater than a predetermined pressure, so that fuel is discharged towardthe engine through the outlet port 208. The valve member 80 restrictsfuel, which is discharged from the fuel pump 10, from causing reverseflow.

In the first embodiment, the end cover 50 defines closed axial end. Thebearing hole 52 substantially axially extends to the closed axial end inthe end cover 50. The closed axial end may be located between the outletport 208 and the bearing hole 52. The closed axial end blocks thebearing hole 52 with respect to an axial direction of the bearing hole52.

In the first embodiment, the bearing hole 52 communicates with theoutlet passage 206, so that fresh fuel passes through the bearing hole52. Thus, the fresh fuel passes through a sliding portion between theshaft 72 and the bearing hole 52. In this structure, fuel can berestricted from being deteriorated due to accumulating between the shaft72 and the bearing hole 52, so that the shaft 72 can be protected fromcorrosion due to deterioration of fuel. Thus, smooth sliding property ofthe bearing hole 52 relative to the shaft 72 can be maintained. Evenwhen foreign matters such as debris caused by ablation flow into thebearing hole 52, the foreign matters immediately flow out toward theoutlet passage 206, so that the foreign matters can be restricted frombeing stuck between the bearing hole 52 and the shaft 72. Thus, smoothsliding property of the bearing hole 52 relative to the shaft 72 can bemaintained.

In the first embodiment, the outlet port 208 is eccentric with respectto the bearing hole 52. The outlet passage 206 having the outlet port208 and the bearing hole 52 directly overlap, so that the outlet passage206 communicates with the bearing hole 52. In this structure, thebearing hole 52 and the outlet passage 206 also serve as communicationpassages, and can be readily communicated with each other.

The outlet passage 206 is substantially linearly defined. Therefore,molding dies can be pulled from each other in the opposite directionafter molding the end cover 50. Thus, the end cover 50 can be integrallymolded of resin.

In the first embodiment, the coil 42 is constructed of the concentratedwinding formed around the tooth 33 of each of the cores 32, so that anoccupancy rate of the winding is enhanced compared with a structure ofdistributed winding, for example. Therefore, a winding space occupied bythe coil 42 is reduced when the number of the winding is constant.Consequently, the motor portion 13 can be reduced, so that the fuel pump10 can be reduced.

In this embodiment, the bearing hole 52 directly supports the shaft 72,so that the number of the components constructing the fuel pump 10 canbe reduced, and manufacturing work for assembling the fuel pump 10 canbe reduced.

Furthermore, the electrically insulative resin material 46 is chargedbetween the teeth 33, which are circumferentially adjacent to eachother, thereby being molded such that the electrically insulative resinmaterial 46 covers the coils 42. Therefore, the coils 42 are protectedfrom corrosion due to exposure to fuel, and the coils 42 can berestricted from being exposed to foreign matters, by applying a simplestructure. Furthermore, the electrically insulative resin material 46 iscapable of protecting the coils 42, which is constructed of theconcentrated winding, from causing deformation in the winding.

Second, Third, and Fourth Embodiments

As shown in FIG. 4, in the second embodiment, an end cover 100 defines abearing hole 102. The bearing hole 102 and the outlet passage 206 do notdirectly overlap. The bearing hole 102 and the outlet passage 206 areradially spaced from each other. The bottom of the bearing hole 102 isblocked. The bearing hole 102 communicates with the outlet passage 206through a communication passage 220.

As shown in FIG. 5, in the third embodiment, an end cover 110 defines abearing hole 112. The bearing hole 112 and the outlet port 208 of theoutlet passage 206 are located substantially on the same axis 120. Thebearing hole 112 and the outlet passage 206 do not directly overlap. Thebearing hole 112 and the outlet passage 206 are radially spaced fromeach other. The bottom of the bearing hole 112 is blocked. The bearinghole 112 communicates with the outlet passage 206 through thecommunication passage 220.

As shown in FIG. 6, in a fuel pump 130 of the fourth embodiment, an endcover 132 defines a bearing hole 134 to which a metallic bearing 140 ispress-inserted. The metallic bearing 140 is a component separate fromthe end cover 132, which is molded of resin. The end cover 132 isintegrally molded of the electrically insulative resin material 46. Theshaft 72 is rotatably supported by the bearing 26 and the bearing 140.The bearing 140 is may be formed of a material of sintered copper alloyor carbon in view of oil resistance.

The bearing hole 134 is defined in the center of the end cover 132. Thebottom of the bearing hole 134 is blocked. The outlet passage 206 iseccentric with respect to the bearing hole 134. The outlet passage 206and the bearing hole 134 directly overlap, and communicate with eachother. In this structure, fresh fuel passes through the bearing hole134, so that the fresh fuel passes through a sliding portion between theshaft 72 and the bearing 140. Thus, fuel can be restricted from beingdeteriorated due to accumulating between the shaft 72 and the bearing140, so that the shaft 72 can be protected from corrosion due todeterioration of fuel. Thus, smooth sliding property of the bearing 140relative to the shaft 72 can be maintained. Even when foreign matterssuch as debris caused by ablation flow into the bearing hole 134, theforeign matters may immediately flow out toward the outlet passage 206,so that the foreign matters can be restricted from being stuck betweenthe bearing 140 and the shaft 72. Thus, smooth sliding property of thebearing 140 relative to the shaft 72 can be maintained.

Other Embodiment

In the above embodiments, the brushless motor is applied to the pumpportion of the fuel pump for generating force driving the pump portionof the fuel pump. The brushless motor may not cause a loss arising in abrush motor due to slide resistance between a commutator and a brush,electric resistance between the commutator and the brush, and fluidresistance applied to a groove, which divides the commutator intosegments. Consequently, the blushless motor is higher than a brush motorin motor efficiency, so that the fuel pump is enhanced in efficiency.The efficiency of the fuel pump is a ratio of an amount of work producedby the fuel pump, i.e., (fuel discharge pressure)×(fuel dischargeamount) relative to electricity supplied to the fuel pump. When theamount of work is constant, as the efficiency of the fuel pumpincreases, a motor portion is reduced in size by applying a brushlessmotor compared with applying a motor (brush motor) with a brush, so thatthe fuel pump can be downsized. Thus, the fuel pump downsized byapplying the brushless motor is preferable, in particular, for a motorcycle.

However, alternatively, a brush motor may be applied to the pumpportion. Even when a brush motor is applied, fuel and foreign matterscan be restricted from accumulating in the bearing hole by communicatingthe bearing hole, which is defined in the end cover and blocked at thebottom thereof, with the outlet passage. Thus, smooth sliding propertyof the bearing hole relative to the shaft can be maintained.

The end cover may be integrally formed by welding multiple resinmembers, instead of integrally molding the end cover of resin. When theend cover is integrally formed with a redundant opening, the redundantopening may be closed using a sealing plug. The end cover may beintegrally formed of a material other than resin. That is, the end covermay be formed of metal, for example.

In the above multiple embodiments, the teeth, which arecircumferentially arranged to construct the stator core, are separatecomponents. Alternatively, the teeth may be integrally formed such thatthe teeth are circumferentially arranged.

In the above multiple embodiments, the pump portion 12 is constructed ofthe turbine pump including the impeller 24. Alternatively, the pumpportion may be constructed of a pump having another structure such as agear pump.

The above structures of the embodiments can be combined as appropriate.

In the above embodiments, the structures of the shaft, the bearing hole,and the end cover are applied to fuel pumps. However, the abovestructures are not limited to the application of the fuel pumps. Theabove structures can be applied to any other fluid pumps.

Various modifications and alternations may be diversely made to theabove embodiments without departing from the spirit of the presentinvention.

1. A fluid pump comprising: a stationary part that has an innercircumferential periphery; a rotator that is rotatable around the innercircumferential periphery, the rotator having a rotation axis, whereinone of the stationary part and the rotator includes at least one coil,the at least one coil generates magnetic force between the stationarypart and the rotator for rotating the rotator when being supplied withelectricity, the fluid pump further comprising: a pump portion that isprovided to one axial end of the rotation axis of the rotator, therotator being adapted to rotating the pump portion for pumping fluid;and a cover that covers an other axial end of the rotation axis of therotator, the cover covering the stationary part on a side of the otheraxial end of the rotation axis, the cover defining an outlet passagethrough which fluid is discharged from the pump portion, wherein thecover has a bearing hole that rotatably supports the other axial end ofthe rotation axis, the bearing hole has a closed bottom, and the coverhas a communication passage that communicates the outlet passage withthe bearing hole.
 2. The fluid pump according to claim 1, wherein the atleast one coil includes a plurality of coils, the stationary partincludes a plurality of teeth, which are circumferentially arranged,each of the plurality of coils is formed by concentrically winding awire around an outer circumferential periphery of each of the pluralityof teeth, the plurality of coils circumferentially generates magneticpoles in inner circumferential peripheries of the plurality of teethwhen being supplied with electricity, the magnetic poles are switched bycontrolling electricity supplied to the plurality of coils, the rotatorhas an outer circumferential periphery that is opposed to the innercircumferential peripheries of the plurality of teeth, and the outercircumferential periphery of the rotator defines magnetic polesdifferent from each other with respect to a rotative direction of therotator.
 3. The fluid pump according to claim 1, wherein the cover isformed of resin, the cover directly supports the rotation axis, and therotation axis is rotatable with respect to the cover.
 4. The fluid pumpaccording to claim 1, further comprising: a metallic bearing that is acomponent separate from the cover, wherein the cover is formed of resin,the metallic bearing is press-inserted into the bearing hole, and themetallic bearing rotatably supports the rotation axis.
 5. The fluid pumpaccording to claim 1, wherein the cover is integrally formed of resin.6. The fluid pump according to claim 1, wherein the outlet passage hasan outlet port that is eccentric with respect to the bearing hole. 7.The fluid pump according to claim 6, wherein the bearing hole and theoutlet passage overlap, and the bearing hole communicates with theoutlet passage.
 8. The fluid pump according to claim 1, wherein thebearing hole substantially axially extends to an closed axial end in thecover, and the closed axial end blocks the bearing hole with respect toan axial direction of the bearing hole.
 9. A fluid pump comprising: astationary part that has an inner circumferential periphery; a rotatorthat is rotatable around the inner circumferential periphery, therotator having a rotation axis, wherein one of the stationary part andthe rotator includes at least one coil, the at least one coil generatesmagnetic force between the stationary part and the rotator for rotatingthe rotator when being supplied with electricity, the fluid pump furthercomprising: a pump portion that is provided to one axial end of therotation axis of the rotator, the rotator being adapted to rotating thepump portion for pumping fluid; and a cover that covers an other axialend of the rotation axis of the rotator, the cover covering thestationary part on a side of the other axial end of the rotation axis,the cover defining an outlet passage through which fluid is dischargedfrom the pump portion, wherein the cover has a bearing hole thatrotatably supports the other axial end of the rotation axis, the bearinghole substantially axially extends to a closed axial end in the cover,the closed axial end blocks the bearing hole with respect to an axialdirection of the bearing hole, and the cover has a communication passagethat communicates the outlet passage with the bearing hole.
 10. Thefluid pump according to claim 9, wherein the communication passage islocated on a side of the bearing hole with respect to the closed axialend.